Patent AU-2018430608-B2 (AU)
Title: Steel plate and method of manufacturing the same
Inventor: TAKAMINE FUMITOSHI
IPC: C21D8/02
Filed: 2018-08-20
Granted: 2021-02-04
Abstract: i 8$ - t'~ T] 40 ;1 J IT d- 51 
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(54) Title: STEEL SHEET AND PRODUCTION METHOD THEREFOR 
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IC(57) Abstract: One embodiment of the present application pertains to a steel sheet having a chemical composition that 
falls within a prescribed range, wherein: the central part of the steel sheet in the thickness direction contains martensite 
and bainite in a total area fraction of at least 99%; in the central part in the sheet thickness direction, the average value of 
en. 4 
prior austenite grains is less than 80 pm, Ceq equals 0.750%-0.800%, Al x N is at least 2.0 x 10- , Ti/N is at most 3.4, 
and 4 x f > 9.00 is satisfied; in the central part in the sheet thickness direction, the three point average of a C-direction 
Charpy test is not less than 47 J at -20°C; and a surface layer
W O 2020/039485 A 1 ||||||||||||||||||||||||||||||||||1|1||||||||||||||||||||||||||||||||||||| 
CL, CN, CO, CR, CU, CZ, DE, DJ, DK, DM, DO, 
DZ, EC, EE, EG, ES, Fl, GB, GD, GE, GH, GM, GT, 
HN, HR, HU, ID, IL, IN, IR, IS, JO, JP, KE, KG, KH, 
KN, KP, KR, KW, KZ, LA, LC, LK, LR, LS, LU, LY, 
MA, MD, ME, MG, MK, MN, MW, MX, MY, MZ, 
NA, NG, NI, NO, NZ, OM, PA, PE, PG, PH, PL, PT, 
QA, RO, RS, RU, RW, SA, SC, SD, SE, SG, SK, SL, 
SM, ST, SV, SY, TH, TJ, TM, TN, TR, TT, TZ, UA, 
UG, US, UZ, VC, VN, ZA, ZM, ZW.  
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TM), - ' (AL, AT, BE, BG, CH, CY, CZ, 
DE, DK, EE, ES, Fl, FR, GB, GR, HR, HU, IE, IS, IT, 
LT, LU, LV, MC, MK, MT, NL, NO, PL, PT, RO, RS, 
SE, SI, SK, SM, TR), OAPI (BF, BJ, CF, CG, CI, CM, 
GA, GN, GQ, GW, KM, ML, MR, NE, SN, TD, TG).  
and the sheet-thickness-direction central part have an HB hardness of at least 350 and a sheet thickness of over 200 nun.  
t /+-f 4 R &y /1Z^t f 4 ) V111 -6--t [MAR% *- 9 9 % L), - T 'J 4 M FP Ij L t, I El tJ 
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